* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* flex-direction 属性定义容器要在哪个方向上堆叠 flex 项目 */
.container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background-color: #000;
    /* 为父元素添加对比度 */
    filter: contrast(30);
}

/* border-radius: 50% 正方形转成圆形 */
.container .drop {
    position: absolute;
    width: 100px;
    height: 100px;
    background-color: #fff;
    border-radius: 50%;
    /* 为子元素添加模糊  */
    filter: blur(20px);
    opacity: 0;
    animation: drop 3s linear infinite;
}

.drop:nth-child(2) {
    transform: translateY(-80px);
    animation-delay: .7s;
}

.drop:nth-child(3) {
    transform: translateY(-130px);
    animation-delay: 1.5s;
}

.collection {
    width: 100px;
    height: 100px;
    background-color: #fff;
    border-radius: 50%;
    filter: blur(20px);
    animation: collection 3s linear infinite;
}

span {
    position: absolute;
    font-family: Arial, Helvetica, sans-serif;
    font-size: 30px;
}


/* 水滴下落动画 */
@keyframes drop {
    0% {
        transform: scale(.7) translateY(-600%);
        opacity: 0;
    }

    50% {
        transform: scale(.4) translateY(-80%);
        opacity: 1;
    }

    100% {
        transform: scale(.3) translateY(0);
    }
}

/* 水滴收集动画 */
@keyframes collection {
    0% {
        transform: scale(1) rotate(0deg);
    }

    50% {
        transform: scale(1.3) rotate(180deg);
        width: 90px;
        border-top-left-radius: 40%;
        border-bottom-left-radius: 45%;
    }

    100% {
        transform: scale(1) rotate(360deg);
    }
}